Problem: A rectangle is $6$ centimeters long. The rectangle is also $3$ centimeters wide. What is its perimeter?
$6\text{ cm}$ $3\text{ cm}$ The perimeter is the total length of all the sides of the shape added together. Add up the lengths of the sides: $ \text{perimeter} = {3} + {6} + {3} + {6} $ $ \text{perimeter} = 18\text{ cm} $